Measuring the distance to far away objects in space can be tricky. We don’t even know the precise distance to even our closest neighbors in the Universe – the Small and Large Magellanic Clouds. But‚ we’re starting to get to the tools to measure it. One type of tool is a Cepheid Variable – a type of star that varies its luminosity in a well-defined pattern. However‚ we don’t know much about their physical properties‚ making utilizing them as distance markers harder. Finding their physical properties would be easier if there were any Cepheid binaries that we could study‚ but astronomers have only found one pair so far. Until a recent paper from researchers from Europe‚ the US‚ and Chile shows measurements of 9 additional binary Cepheid systems – enough that we can start understanding the statistics of these useful distance markers. Like traditional stars‚ binary Cepheid systems result when two stars orbit around each other. In this case‚ both of those stars must be Cepheids – meaning they are massive compared to our Sun and much brighter. In addition‚ their luminosity must vary in a repeatable pattern so that we can track it consistently. All of those features can vary a lot if two stars change in luminosity but at different rates and phases around each other. It’s difficult to parse out which star is waxing‚ which is waning‚ and which direction they are moving in‚ both compared to us and each other. Long periods of observation are required to fix some of those variables‚ and that is precisely what the new paper describes. The researchers looked at nine sets of Cepheids that were believed to be binary systems but hadn’t yet been confirmed due to the difficulty of separating the two stars from each other. They pulled data from the Optical Gravitational Lensing Experiment (OGLE) database‚ a variable star observation project run by the University of Warsaw for over 30 years. In so doing‚ they could confirm‚ for the first time‚ that each of these suspected binaries contained two separate stars. Those nine binary systems were located in the Small and Large Magellanic Cloud and the Milky Way. One located in the Milky Way is by far the closest‚ at only 11 kiloparsecs (about 3000 light-years) away. The researchers also had good luck because of the length of orbital periods of the binaries they studied – most were over five years‚ and a shorter observational data set might not have caught them.  Understanding how these systems exist and where they are is just the first step. Using them for more helpful science is the next. The most obvious way to do so is to increase our understanding of Cepheids. Despite being one of the most commonly used distance markers in the Universe‚ we know surprisingly little about how they form‚ what they’re made of‚ or their life cycle. Closely studying a binary system‚ where the stars interact‚ could help shed light (figuratively in this sense) on some of those properties. Calibrated Period-luminosity Relationship for CepheidsCredit – NASA As the authors point out in their paper‚ this is part of a long-term ongoing project – they were also part of the team that confirmed the original Cepheid binary system back in 2014. OGLE continues to collect more data‚ as are other sky surveys‚ and there are likely more Cepheid binaries out there. Every new discovery will help improve our statistical understanding of these critical distance markers – we just need to take the time to find them first. Learn More:Pilecki et al. – Cepheids with giant companions II. – Spectroscopic confirmation of nine new double-lined binary systems composed of two CepheidsUT – What are Cepheid Variables?UT – Polaris is the Closest‚ Brightest Cepheid Variable. Very Recently‚ Something Changed.UT – Astronomers Rule Out One Explanation for the Hubble Tension Lead Image:RS Puppis ‚ one of the brightest known Cepheid variable stars in the Milky Way galaxyCredit – NASA‚ ESA‚ and the Hubble Heritage Team The post Astronomers Only Knew of a Single Binary Cepheid System. Now They Just Found Nine More appeared first on Universe Today.

The Solar and Heliospheric Observatory (SOHO) was designed to examine the Sun‚ but as a side benefit‚ it has been the most successful comet hunter ever built. Since early in the mission‚ citizen scientists have been scanning through the telescope’s data‚ searching for icy objects passing close to the Sun. An astronomy student in Czechia has identified 200 comets in SOHO data since he started in 2009 at the age of 13. He recently spotted the observatory’s 5‚000th comet. “Prior to the launch of the SOHO mission and the Sungrazer Project‚ there were only a couple dozen sungrazing comets on record – that’s all we knew existed‚” said Karl Battams‚ who is the principal investigator for the Sungrazer Project‚ the citizen science project that was launched after so many comets started showing up in the data. “The fact that we’ve finally reached this milestone – 5000 comets – is just unbelievable to me.” SOHO moves around the Sun on the sunward side of Earth‚ where it enjoys a clear‚ uninterrupted view of the Sun‚ by slowly orbiting around Lagrange point L1.  That means it has been observing the Sun 24 hours a day‚ 365 days a year without interruptions since shortly after it launched in 1995. With this view‚ SOHO can easily spot the kind of comet that’s known as a sungrazer – so named because of their close approach to the Sun. Many of these comets don’t survive their close pass to the Sun. Many congratulations to Hanjie Tan (@HonkitTan) for making that 5‚000th discovery! Hanjie has been discovering comets with the Sungrazer Project since he was 13yrs old‚ and is now pursuing for his PhD studying asteroids! pic.twitter.com/wa51ZlVnjm— Karl Battams (@SungrazerComets) March 27‚ 2024 Hanjie Tan is the student who discovered the 5‚000th comet. Inspired by his many years of searching for comets‚ Tan is now an astronomy PhD student in Prague‚ Czechia‚ studying comets and asteroids. The small comet that he spotted is part of the ‘Marsden group’ of comets‚ named after the British astronomer Brian Marsden‚ who first recognized the group based on SOHO observations. Marsden group comets are thought to be pieces shed by the much bigger Comet 96P/Machholz‚ which SOHO observes as it passes close to the Sun every 5.3 years. “The Marsden group comets represent only about 1.5% of all SOHO comet discoveries‚” said Tan in an ESA press release‚ “so finding this one as the 5000th SOHO comet felt incredibly fortunate. It’s really exciting to be the first to see comets get bright near the Sun after they’ve been travelling through space for thousands of years.” Artist’s impression of the SOHO spacecraft studying the Sun. Credit: NASA/ESA. The SOHO mission has now been operational for almost 30 years. It’s almost been lost twice and is now flying without the use of its gyroscopes‚ which help it point precisely. Engineers have figured out a way to work around the issue. It’s longevity has not only provided an incredible treasure trove of data about the Sun‚ but it also has allowed the spacecraft to become the most prolific discoverer of comets in astronomical history. Related: 22 years of the Sun from SOHO Launched in 1995‚ SOHO studies the Sun from its interior to its outer atmosphere‚ providing unique views and investigating the cause of the solar wind. During the last three decades‚ SOHO has become the most prolific discoverer of comets in astronomical history. “A huge congratulations to EVERYONE who has ever contributed to Sungrazer‚” Battams said on Twitter. “Hanjie may have found #5000‚ but it took 24-years of combined volunteer ‘amateur’ scientist efforts to find the other 4‚999. This was a team effort‚ and I’m so thankful to all who have helped!” The post Someone Just Found SOHO's 5‚000th Comet appeared first on Universe Today.

Anyone can be an underachiever‚ even if you’re an astronomical singularity weighing over four billion times the mass of the Sun. At least the quasar H1821+643 doesn’t have parents to be disappointed in it. But its underachievement could shed light on how quasars‚ a potent type of black hole‚ can come to influence entire clusters of galaxies‚ as described in a new paper from researchers at the University of Nottingham and Harvard. Using X-ray data from the Chandra observatory‚ the researchers looked closely at H1821+643 and decided it influenced its local environment much less than expected. Granted‚ a lot was expected of it – quasars are super powerful black holes that rapidly pull in new material rapidly and eject radiation as well as sometimes emitting powerful streams of particles. In particular‚ H1821+643 is a quasar located about 3.4 billion light-years away from Earth at the center of a cluster of galaxies.  Both the quasar and its surrounding galaxy are shrouded in a field of hot gas that showed up as a fuzzy haze in Chandra’s X-ray dataset. That fuzzy haze‚ which would let astronomers understand what was happening to the gas in the galaxy at large‚ was massively overwhelmed by the brightness of the X-rays emitted from the quasar itself. Fraser describes what quasars are. To study the effects of the quasar on the location gas population‚ the researchers had to remove the effects of its own X-rays‚ leaving only the light emitted from the gas itself. They found that the gas is significantly less hot than might be expected given its proximity to such a forceful quasar‚ showing that the quasar itself isn’t outputting as much energy as might otherwise be expected. Counterintuitively‚ the Chandra data shows that the density of gas around the quasar is higher. At the same time‚ the temperature is cooler than areas of the galaxy that are further away from the center. If the quasar were emitting the typical series of outbursts‚ they would have expected there to be not as much gas close to the quasar itself‚ as the outbursts would have blown it away and that what gas there was close in would be heated to extraordinarily high temperature by those same outbursts. Without those outbursts‚ though‚ the local environment appears to be rife for star formation. The authors estimate that gas equivalent to about 3‚000 times the mass of our Sun cools below the point where it emits X-rays every year. Some of that cooling gas is formed into about 120 solar masses worth of new stars yearly‚ while the black hole itself swallows up another 40 solar masses. What happens with the thousands of solar masses of gas left over after those two processes is anyone’s guess. Here’s a fund‚ speculative video from Fraser about whether our own supermassive black hole could become a quasar. However‚ the quasar itself isn’t cooling the gas surrounding it. At least not much. This process can happen when photons emitted from the black hole run into the electrons of the surrounding gas‚ resulting in an energy transfer that increases the energy of the photon but decreases the energy of the electron – hence causing the gas to cool down. While that process might be ongoing near H1821-643‚ the authors calculate that it would only explain a small percentage of the cooling of the gas they observed. In short‚ much is still unknown about this seemingly unique quasar system. Studying it further can help scientists understand the influence these massive singularities can have on their immediate surroundings and physical properties more generally. At least‚ no matter what H1821-643’s physical properties might be‚ it won’t be getting chewed out by its parents. Learn More:NASA / CXC – NASA’s Chandra Identifies an Underachieving Black HoleRussell et al. – A cooling flow around the low-redshift quasar H1821+643UT – What Is A Quasar?UT – This New Map of 1.3 Million Quasars Is A Powerful Tool Lead Image:Image of the H1821-643 quasar.Credit: X-ray: NASA/CXC/Univ. of Nottingham/H. Russell et al. Radio: NSF/NRAO/VLA Image Processing: NASA/CXC/SAO/N. Wolk The post This Black Hole is a Total Underachiever appeared first on Universe Today.

We know how stars form. Clouds of interstellar gas and dust gravitationally collapse to form a burst of star formation we call a stellar nursery. Eventually‚ the cores of these protostars become dense enough to ignite their nuclear furnace and shine as true stars. But catching stars in that birth-moment act is difficult. Young stars are often hidden deep within their dense progenitor cloud‚ so we don’t see their light until they’ve already started shining. But new observations from the Hubble Space Telescope have given us our earliest glimpse of a shiny new star. You can see this image above‚ which captures the dusty region of the FS Tau system. The bright star just to the right of center is FS Tau A‚ which is a young star just 2.8 million years old. An infant compared to our Sun’s 4.6 billion years. But the exciting discovery is a bit higher and further right‚ known as FS Tau B. That line of dust obscuring the protostar is its protoplanetary disk seen edge-on. The light coming from the obscured star isn’t produced by nuclear fusion‚ but rather the late stages of gravitational collapse. You can also see that the protostar has begun to produce radiant jets‚ which are reflected against the dusty nebula as regions of blue light. Because of this reflected light‚ FS Tau B is classified as a Herbig-Haro (HH) object. HH objects are great for helping astronomers understand the early dynamics of these stars. FS Tau B is likely in the early stages of becoming a T Tauri star. These are sun-like stars just on the edge of becoming true stars. They can be quite active‚ with starspots and large flares‚ but can take 100 million years for one to ignite their cores and settle into a true main-sequence star. As that happens‚ protoplanets will form within the dusty disk‚ ready to become full planets in time. You can find more information about the FS Tau system‚ as well as high-resolution images and videos‚ on the ESA Hubble website. The post Hubble Sees a Star About to Ignite appeared first on Universe Today.

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